How to choose an inverter

Inverter for use at home has become a necessity than a luxury with frequent power cuts across India. The sales of popular brands like APC, Luminous, Sukam, Microtek, Amaron, V guard, Hykon with good reviews have been zooming even though the prices have been rising. People now want to run all home appliances including air conditioners, televisions and refrigerators for their convenience.

WHAT IS INVERTER

A power inverter converts DC power to standard home AC power. This lets you run AC electrical equipments during power outages conveniently.

TYPICAL USES

Inverters normally have one or more standard outlets to power laptops, small TVs, DVD players and other home appliances like light and fans.

FEATURES

Ground Fault Protection

If the inverter gets damp or wet Ground fault protection instantly turns off the inverter. The inverter turns itself back on if the problems are fixed. GFCI feature protects people from electrical shocks and fire.

Transfer Switch

Power inverters have a built-in transfer switch which switches from inverter power to utility power when electricity comes. The transfer switch allows external power to be transferred to appliances automatically.

Solar Power Support

Inverter today also support solar power system. They convert DC power generated by solar panels and store it in batteries. These get transformed to power which can be used for home appliances. These systems can be can be expensive and hence might not be advisable for individual homes.

POWER INVERTER OR GENERATOR?

Generator typically is needed for higher power needs.
An inverter is more economical power alternative to run items under 1000W and is ideal for small appliances like light, fan, laptop, TV other low load appliances. To operate a refrigerator, washing machine, AC and other high load appliances, a generator is a better option.

For power consumption above 2000W, a generator will be a better option.

DIFFERENCE BETWEEN INVERTER AND UPS

Both provide backup when there is a power outage. In case of UPS the switch is instantaneous whereas in case of inverters there is a lag in switch.
Hence in case of critical applications like computers a UPS is needed.
For household appliances like fan, light, cooler etc. the gap is fine and hence an inverter works well.
An inverter is typically cheaper than a UPS.

HOME APPLIANCE POWER USAGE

The typical usage of power appliances which you can use for approximate calculations is as in the table below ( do check the actual appliances wattage for caculating wattage):

Appliance

Power (in Watts)

Starting (in Watts)

Fan

100

200

Tubelight

50

100

TV

120

240

Laptop

75

100

Washing machine - with heater

1200

2400

Washing machine - without heater

2000

3200

Air Conditioner (1.5T)

2200

4000

Air Cooler

1000

2000

Refrigerator (150W)

150

300

CHOOSING THE RIGHT SIZE

The size of inverter is measured in watts (W). The amount of wattage needed depends on the appliances that need to run.
Many appliances have the wattage rated on the product. Wattage rating can also be calculated as:

Volts x Amps = Watts

The sum of wattage of all appliance should be within the specifications of the inverter. e.g. if you are planning a 2 outlet inverter then take the sum of wattage and add another 50% to account for any surges in power draw. For example if your tubelight draws 50W and fan draws 50W you should go for at least a 150W ( 50W+50W+50% of (50W+50W) ) inverter.
Make sure the power of the inverter is listed as "continuous". They should not draw the wattage for a short period of time and then will shut off, reset themselves and resume functioning. Such outages can be frustrating and harmful to the appliances.
There are certain appliances that need a start-up wattage which is higher than the normal running wattage e.g. a washing machine that runs at 500W might need 1000W to start. So the inverter rating should have considered 1000W instead of 500W as otherwise the washing machine will not start

TYPES

Power inverters produce one of two different types of wave output:

Modified Sine Wave

True Sine Wave

Modified Sine Wave

Modified sine wave inverter are most popular and cheaper. They are efficient enough to run most hone appliances properly. They are also smaller than other types of inverters.

True Sine Wave

True sine wave inverters are the most expensive. They deliver the most consistent, highest quality wave output.
These can have high surge capacity which indicates that they can exceed the rated wattage for limited time which is helpful in starting appliances.
Some equipment requires a true sine wave like laptops, battery chargers and so on. AC appliances will run on a true sine wave inverter.

Modified and True Sinewave Output

Advantages of True Sine Wave

Have very low distortion and have clean power like normal electricity.

Appliances using induction like microwave ovens run faster, quieter and cooler.